This is a Phase I trial of an improved 14.18 antibody linked to IL-2 and directed against the GD2 ganglioside found on the surface of melanomas, sarcomas, and neuroblastomas. The "humanized" antibody is expected to yield a diminished HAMA response; the IL-2 is intended to attract and stimulate cytotoxic T cells to destroy the "labeled" cells. Patients with GD2+ tumors will receive three-day cycles of four hour intravenous infusions of the fusion protein, starting at a daily dose of 1 mg/m2/day. Subsequent cohorts of N=1 will be treated at 2, 4, 6 and 9 mg/m2/day. The two-stage design will then explore the MTD in cohorts of three.